Technical

Exporting a component

Each of the ATLAS components (search, i-publisher, tmstore, pre-proc, processing, autocat, summarizer) are based in the OSGi architecuture. This means that each component consists of OSGi runtime (namely Equinox http://eclipse.org/equinox/), a set of bindles (plugins), launcher and launcher configuration. Each component is described as an "Eclipse product" and is experted as such from the Eclipse development environment.

Note:  A later version of the ATLAS component will be shipped with build scripts, thus minimizing the need of an additional building GUI environemnt.

The launcher and the launcher configuration are created automatically, based on the description of the "Eclipse product". The ATLAS component can be exported in both the Linux (32/64bits) and Windows (32/64bits) environments. The only platform-dependent part of the exported components is the launcher executable file.

Configuring a component

While the launcher configuration is used for configuring the launcher, the component configuration is used to provide configuration to the business logic of a component. Each component is convigured through the "org.osgi.service.cm.ConfigurationAdmin" OSGi service by providing an OSGi fragment which contians configuration properties files. Each business service that needs access to the configuration should bind the ConfigurationAdmin service and request the needed configuration by its identificator. Typically, the indentificator is based on the name of the business service requiring this configuration.

The image below shows the layout of the fragment bundle and its content.

Starting a component

Starting an exported component is simple - one should only start the laucher (or double-click on it). However, all ATLAS component are meant to run as daemons and the simple startup option will not be sufficient for this. There are two options for how an ATLAS component is strated as daemon:

1. Using a stratup script (start.sh) - the shell script shown below is starting the component launcher as a daemon and redirects its output stream to a log file:
   
2. Using OS-specific techniques - this appraoch requires administrative privilidges on Windows and root access on Linux. One should create an NT service on Windows or "init.d" script on Linux.